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Biomedical subjects

A Suzaki

Publications and source records attributed to A Suzaki.

7 recordsLinked to original sources
PubMed1995

[An outbreak of acute pulmonary histoplasmosis among travelers to a bat-inhabited cave in Brazil].

Histoplasmosis is known to be endemic in various parts of the world, especially in North and Latin America. In Japan, Histoplasma capsulatum has rarely been isolated from the natural environment. To date, only seven cases of histoplasmosis have been reported in Japan including some that were contracted in foreign countries. Herein, we report the occurrence of acute histoplasmosis among Japanese travelers who were exposed to bat guano in a cave near Manaus, Brazil. A group of 8 Japanese travelers entered a cave for a total of 2 hours in March, 1993. All the visitors had been healthy and had no history of abnormal chest roentgenograms. From 10 to 20 days after the exposure, 7 (87.5%) of the 8 individuals developed abnormal symptoms including fever, malaise, loss of appetite, myalgia, arthralgia, chest pain and dry cough. Five (62.5%) had nodular infiltrative shadows with or without hilar lymphadenopathy in the chest roentgenograms. Eight (100%) of the individuals showed serologic evidence of histoplasmosis. Despite the small number of subjects, this high rate of infection may be related to the fact that the subjects stayed in an enclosed area where air exchange was minimal, at the end of a deep cave infested with numerous bats. The cave involved has never been documented as being endemic for histoplasmosis. The threat of H. capsulatum infection in bat-inhabited caves should be emphasized to travelers and also to physicians.

Adult↗
PubMed1993

Specific hepatocyte endothelin receptors and the direct effect of endothelin on protein synthesis.

High affinity binding sites for endothelin (ET)-1 were identified on mouse parenchymal hepatocytes. The binding of 125I-ET-1 at its site was specific, saturable, and time dependent, but dissociation of the receptor-bound ligand was minimal. Scatchard analysis of the binding data revealed the presence of a non-interacting, single class of high-affinity binding sites on hepatocytes. The dissociation binding constant (Kd) and the maximal binding capacity (Bmax) were determined as 2.1 x 10(-10) M and 3.0 x 10(2) sites/cell, respectively. Unlabeled ET-1 competitively inhibited the binding of 125I-ET-1 to primary cultured mouse hepatocytes with a concentration for half-maximal inhibition (IC50) of 2.0 x 10(-10) M. ET-1 apparently enhanced total protein synthesis in primary cultured mouse hepatocytes concentration ranging from 3 x 10(-11) M to 3 x 10(-8) M in a dose-dependent manner. These data indicate that specific receptor for ET-1 is present in the mouse liver and suggest for the first time that hepatocyte protein synthesis is involved in its direct, agonistic effect.

Animals↗
PubMed1992

Stimulation of anchorage-independent cell growth by endothelin in NRK 49F cells.

Endothelin (ET) is a vasoconstrictor peptide originally isolated from vascular endothelial cells. Recent studies have revealed that ET has many biological functions including growth factor-like activity. The present study aims to clarify whether ET-1 possesses the ability to stimulate anchorage-independent cellular growth, an indicator of factors with transforming activity. We found that NRK 49F cells possess a large number of high-affinity ET-1 receptors; labeled 125I-ET-1 binding was displaced by unlabeled ET-2 in a similar dose response, but in the case of ET-3, 100-fold more was required. Specific 125I-ET-3 binding was undetectable in NRK 49F cells, indicating that ET receptors in NRK 49F cells are ET-1/ET-2 selective. NRK 49F is a cell line which is most commonly used to assay for anchorage-independent cellular growth. Therefore, we explored whether ETs promote anchorage-independent cellular growth in this cell line. ET-1 and ET-2 stimulated NRK colony formation dose dependently in the presence of 1 nM epidermal growth factor (EGF). In contrast, ET-3 did not have colony-stimulating ability. In the presence of EGF, the maximal effect of ET-1 was approximately 90% of that of transforming growth factor-beta. Moreover, in the presence of maximal stimulating concentrations of EGF and transforming growth factor-beta, ET-1 additionally induced colony formation. These results indicate that ET-1 and -2 possess transforming growth factor-like activity for NRK 49F cells. Since ET-1 and -2 increased intracellular calcium levels, this ion may participate in signal transduction pathways by which ET-1 and -2 promote colony formation.

Animals↗
PubMed1990

Production of endothelin in human cancer cell lines.

Endothelin (ET)-1 is a vasoconstrictor peptide derived from endothelial cells and now known to be a local regulator of vascular tonus. Recent studies, however, have revealed that ET-1 functions also as growth factor in various cells. By using a specific ET-1 radioimmunoassay, immunoreactive (IR) ET-1, ranging from 4.2 to 150 pM (minimum detectable amount, 4.0 pM), was detected in 13 of 42 human cancer cell lines. The frequencies of IR-ET-1 production and its concentrations were high in mammary, pancreatic, and colon carcinoma cell lines. IR-ET-1 produced by cancer cells possessed the same molecular size as synthetic ET-1 and also had ET-1-like biological activity. Moreover, Northern blot analysis revealed bands corresponding to ET-1 mRNA in cancer cell lines, indicating that IR-ET-1 produced by cancer cells is a product of the ET-1 gene. Since ET-1 in the spent media is present in a sufficient amount to stimulate cellular growth, we sought ET-1 receptors in four pancreatic carcinoma cell lines and human skin fibroblasts. No ET-1 receptors were detected in the pancreatic carcinoma cell lines. However, human skin fibroblasts possessed a large number of ET-1 receptors. This finding raises the possibility that ET-1 produced by cancer cells plays a modulatory role in the growth of stromal cells surrounding cancer cells.

Cell Line↗